Plate clamp



Get. 9, 1945.

C. W. HARROLD E'I'AL PLATE CLAMP Filed Oct. 9, 1942 3v Sheets-Sheet 1 Mil" Patented Oct. 9, 1945 UNITED STATES PATENT OFFICE Charles W. Harrold, University Heights, and Earl rW. Curtis, Maple Heights, Ohio, assignors to .Harris-Seybold Potter Company, Cleveland, Ohio, a corporation of Delaware Application October 9, 1942, Serial No. 461,414

16 Claims. (Cl. lOl-415.1)

'I'his invention relates to plate clamps, that is to say means for 'clamping `theends of a, plate onto one of the elements of a printing couple. Primarily the invention has to do with means for clamping and tensioning aplate on the plate cyl inder of a lithographie or gravure printing press, the cylinder being provided with a gap in which the plate clamp is positioned radially inward of the cylinder surface.

.One of the objects .of the invention is the provision of simple 4means for gripping Athe ends of a plate. Another object is the provision of plate clamping means occupying a relatively small space.

Anotherobject is the Vprovision of operating means which functions to actuat'e the plate gripping means and thereafter to move theclarnpv assembly for exerting a pull to draw the plate tightly against the cylinder wall.

Other objects and features of novelty appear as we proceed with the description of those Aeinbodirnents of the invention which, for the pur.; poses of the present application, we have illus-l trated in the accompanying drawings; in which f Fig. 1 is a planv view of a plate cylinder em'- bodyinga plate clamp constructed in accordance with the invention.

Figs. 2 and 3 .are fragmental cross-sectional views on a larger scale, taken substantially along the lines 2-2 and 3-3 vof Fig. l, and showing ka plate in operative position.

Fig. 4 i-s a fragmental cross-sectional view on a still larger scale showing details of one of the clamp assemblies.

Fig. 5 is a side elevational view of one of the clamping bars.

Fig. 6 is a bottom plan View of the same.

Fig. 7 is a, fragmental perspective View of one of the assemblies.

.Fi-g. 8 is a detail perspective View of one element of the operating or adjusting means.

Fig. 9 is a fragmental planview of .a modified form of the invention, and

Fig. 10 is a cross-sectional View taken substantially on line Ill-I0 of Fig. 9.

Referring iirst to Figs. 1 to 8 inclusive, a plate cylinder of-usual construction is shown at I0. It is provided with a gap II, which is also of usual form. The plate clamp, which constitutes vthe subject of the invention, is mounted in this gap. One end of the plate, which is marked I2, is secured within a single assembly comprising an elongated housing I3. The other end is 'preferablyinounted in `three separate assemblies, each of which comprises a housing I4,

The housing I3 and the housings VIII are ar.- ranged to slide on the bottom surface of the gap toward and away from each other.v They `are held against movement away from the bottom surf-ace of thegap by means of retainer plates I5 and IB. Each retainer plate I5 is formed to engage the outer ,Surface of housing I3 aswell as the outer surfaces of two adjacent housings I`4 being anchored in the cylinder between the two housings .by screws Il or the like which extend through spacing sleeves indicated at vI 8*. The end retaining plates I6, each of which engages but one housing I4, are similarly mounted by means of screws I9 and spacers 29. Y Additional mounting means for the latter.comprises for each plate a screw '2| that projects'through a Yshort spacing sleeve 22 which yrests upon a block 2'3. Screw 2| extends through a hole in the block into the threaded opening in the cylinder, .as shown in Fig. 3. The opposite end of block 23 is anchored by a screw 24 which extends through the block into a threaded opening in the cylinder, as also shown in Fig. 3. y

The housing I3 is provided with a longitudinal groove `25. The sides of this groove as shown are planar surfaces and are vpreferably parallel, the upper side 26 vbeing narrower than the bottom side because ofthe necessity for clearing thepath of the cylinder surface as the cylinder rotates. The plate I2-is gripped between this groove wall 26 anda clamping 'bar 2l which Vis mounted in the groove and is capable of being rocked transe versely, as by means of ,a pin wrench (not shown) inserted into one of lthe end holes 28 through the bar. liy lmeans of such a wrench the Ibar maybe tilted or rocked transversely.

As illustrated specicaily in Figs. 4 and l the upper and lower 'surfaces 29 and y3D respectively of the bar are :cam shaped, the surface -29 being provided preferably with longitudinal serrations 3I for better gripping action. These surfaces 29 and .30 are so arranged and proportioned with respect tothe width of the .groove 25 that when the `har is' rocked in the anti-clockwise direction, as viewed in Figs. l2', 4 and V'7, a ,line joining the high spots of the twocam surfaces willrmove toward the vertical, thereby tending to wedge the bar betweenthe side walls o f the groove 2.5. As Will be apparent also, thiswledeins action is promotedor enhanced by. any force tending tupun the plate out of the clamp, that is toward Vthe i although we prefer to do so by other means, as will be presently described.

When the force tending to hold bar 21 in its plate gripping position is relieved, it is desirable to have the bar rock clockwise automatically so as to release the plate end. This may be accomplished by means of a coil spring 32 which seats against a screw plug 33, the head of which is threaded into a threaded socket in the top of the housing I3. The lower end of this spring seats in a pocket 34 formed in a lateral extension 35 of -bar 21. This extension may be conveniently formed with a round shank 36 which may be driven into a suitable hole in the bar. Anydesired number of these spring assemblies may be employed, two being shown herein. In order to accommodate the bar extensions and the springs 32, the housing I3 must be provided at the proper points with cavities 31 opening into the groove 25.

In this form of the invention we provide common operating means-for first rocking the clamping bar 21 toward plate gripping position, which is the position illustrated in the drawings, and

'thereafter for pulling the clamping assembly,

that is the housing I3 and the bar 21, away from the adjacent wall 38 of the cylinder gap. The operating means for this assembly may comprise two or more units, three being illustrated herein. Each such unit comprises a screw 4U provided with a head 4I having radial holes 42 therein for i -the reception of a pin wrench in order` to facilitate-manipulation. This screw projects through an internally threaded sleeve `43 which is slidably mounted in a smooth hole 44 in the housing I3 and extends through an arched opening in the bar 21, likerthe opening 45 in Figs. 5 and 6. At its outer end this sleeve has a head 46 with laterally extending wings which are received vin a cavity 41 in the outer side of bar 21 and which engage curved surfaces 48 at the bottom of the bar, tending `to turn the bar in the plate gripping position against the action of springs 32, that is when a pull is exerted upon the sleeve in a direction toward the right as seen in Figs. 4 and 1.

While the screw 40 may be made in one piece if desired, we prefer to form the inner end of a separate hardened steel plug 49 having a shank freely fitted -into an axial hole in the end of the screw proper.A When the screw 40 is threaded into the sleeve 43 the plug 49 is caused to engage the wall 38 of the gap, after which it remains stationary while the screw turns.V Continued turning of the screwV in the same direction causes the head 46 of sleeve 43 to -pull against the curved surface 48 of bar 21, thereby rocking the bar into plate gripping position. As soon as vthe -bar is tightly wedged against the plate and can turn no further, additional operation of the screw 4B eX- erts a pull through bar 21 upon the, housing I3,

and the entire assembly then moves toward the right.

Each of the three sections of the clamp on the side opposite the housing I3 and bar 21 functions in the same way as the assembly already described, except that there is but one operating springs 55, the ends of which set into sockets in the respective housings. When the screws 46 are backed off, the springs 55 push the housings outward as far as they will go.

When the two ends of the plate I2 are in the bite or the clamp, the plate may be adjusted lengthwise of the roller. For this purpose we mount in the ends of the housing I3 two adjustingscrews 56. The heads .of these screws are caused to bear against the adjacent ends of the gap in the cylinder to fix the longitudinal position of the housing, and when the latter needs to be moved one way or the other one of the screws 56 is turned towardthe right .and the other toward the left a corresponding amount. The outer extremities of the two end housing I4 are threaded to receive screws 51 which project through slots 58 in blocks 23, and the heads of which bear against washers 59. When it is desired to adjust this end of the plate longitudinally of the cylinder in one direction or the other, one of the screws 51 is loosened 'and the other screw is then threaded inwardly to exert a pull upon the adjacent housing I4, Vand through the plate itself upon the remaining housings I4. When the desired adjustment is attained the first screw 51 is then tightened so that theplate end is held in the desired position.

When a plate is to be removed and another plate mounted on the cylinder, the operator first loosens all of the screws 40, permitting the springs 33 to rock the clamping bars to non-gripping position and permitting the springs 55 to push the housing I3 and the housings I4 outwardly against the side walls of the gap. The plate may then be removed. One end of a new plate is then inserted between the clamping bar 21 and the groove wall 26 of housing I3, after which the screws 40 for that housing are threaded outwardly far enough to cause the plate to be gripped. The plate is then wound about the surface of the cylinder and its opposite end is pushed into position between the groove walls 6U and the clamping .bars 50,50 and 52. The three screws 4l) mounted in the housings I4 are then operated to rock the said clamping bars into position to grip that end of the plate. Now all of the screws 40 are turned in succession a small amount at a time until the plate approaches the cylinder rather closely, after which the screws 40 in housings I4 are adjusted to effect final tightening of the plate onto the cylinder and to give it any slight variation from absolute parallelism which variation may be required to bring the form into register. Adjustment of the plate lengthwise of the cylinder may be effected at any time before -the plate is clamped tightly, or it may be effected thereafter by rst looseningthe screws 40 holding one or both ends of the plate. f s

In the form of the invention illustrated in Figs. 9 and 10 any suitable means may be assumed for securing one end of theplate, and this means may be incorporated in'a movable housing V10 similar to the housing I3 previously described. Opposite the housing 107th'ere may be a plurality of housings 1I, one only-of V which isillustrated, these housings being s lidable in the gap 12 of the cylinder 13 for the 'same purpose as in the case of the housings I4. kCompression springs 14 ten'd to separate the housings 10 and 1I inthe same manner as described for the rst form Aof the invention.

The Aplate gripping means for the housingl-I comprises a clamping bar- 15 of round Acrosssection mounted inagroove 96 inV the housing.

Atleastone of the side walls ofthi's grooveis viin'- cl-ined'so that the -groovefis constricted somewhat at its mouth. MeansI are provided-for causing bar 1'5- totil-tfor rock about one or more longitudinal fulcrum lline's at `the bottom of the bar; In Ythe illustrated case this means consists otra pairoi pinsll which take `into sockets 1-1 in: theban suil'cientclearance being provided to permitrocking of lthe bar about the-line -joinirig the points 19. In some cases lthe bar may also rock about the -line joining the points |-8-. The rocking of thebarmaybe effected by the operator by means of a -pinwrench inserted in the hole 810 through the bar atene endthereof. v

Irl-order that an. end of plate 8l' may be Lin--f sortedi in the clamp the operator rocks Vo'r tilts the bar 'l5 counterclockwise from the positionillustrated in Fig. 10, which results irr the -bar moving away from the inclined wall 822` of the groove. After they end of' the plate is inserted the bar l5'- is again rockedlclockwise-to: wedge -it against the plate 811 and rml'y grip the latter; Then a screw 8`3, similar to the screws 40 of the iirst described form of the. invention, may be threaded into the housing. 12| until the end of the screw bears .against the wall of the gap, after which ,further rotation of the screw' in the same direction will draw the assembly, comprising bar l`5- and housing l-I, toward the left as viewed in Fig; 110; thereby drawing the plate into tight en gagernent with the cylinder surface. When the plateis -tobe removed the screw is of course turned in the opposite direction, thereby permitting springs'l to move the clamp assembly outward or toward the gapwall.

In this form of the invention we may provide means for releasably holding thebar l5Y in .either its operative or inoperative position, whichmeans mayl comprise a slide 84- mounted in a transverse'bore in the housing 'il and' having a pocket 8'5 of asize to looselyengage diametrically oppo-r site points ot the bar l5, a socket 85 being formed in the cylinder 13 toreceive the .end of slide 84 wfhen'the latter is in its illustrated position. Two detent sockets 81 and 8B are formed in the slide to receive a ol'etentrlly which is' urged downwardly by acoil spring'gll. The upper end oi this spring bears against a plug 91 threaded into the upper endf of the bore 'in which the detent .is mounted to slide.A This springk is adapted to yield when the detent is cam-med upwardly by the movement of the slide, andthe slide in turn is moved when' the ba-r15 is rocked about the line joining points 1-9. Housing "Il maybe heldl againstradiallyoutward movement by a bolt 9-2 and washer 93 engagingy the top surface of the housing, theshank of the bolt extending down through av hole 94 in the housing of large enough diameter to permit the necessary movement of the housing.

It will bey obvious that this form of the invention functions similarly to the'functioning of the first describedV form, in*v that any strain upon the plate Sltending to separate it from the clamping assembly merely strengthens the gripof the clampv upon the plate.

VHaving thus described our invention, we claim:r

l1. In a plate cla-mp for use with a cylinder having a gap therein and having means for securing one end of the plate, an elongated housing adapted to be mounted in the gap, said housing having a longitudinal groove therein for reception ofthe opposite end of said plate, a bar in said groove adapted when rocked transversely to be wedged between one wall of the groove and said plate backed by the other wall of the groove,

and' interengaging meansbetween the housing and the bar on the side of the groove'. remote fromitspl'atel engaging wall for providing an abutment against which the bar may bear when itis rocked in a direction to increase. plate hold-- ing pressure. Y v' y I Y 2. In a plate clampk for use with a cylinder having a gap therein and having means for securing one end of the plate; an elongated A-l`io'i-1s-- ing-adapted- `tofbe mounted i'nthe gap, saidA house ing having a longitudinal' groove therein for re-v cepti'on of theopposite end of -said plate,A a bai" in said groove adapted when rocked transversely to be wedged between; one wall of' the groove and said plate backed bythe other wall of the groove the' plate engaging surface of the groove being planar and the plate-engaging Asurface of said bar being cam shaped, 'and interengaging'means betweenfthe housing and the bar on the side-of the groove remote from-'its "plate-engagingV wall for providing an abutment against which the bar" mayfb'ear whenit isrocked a direction to in-v crease plate holding pressure.

3-. lin a plate-clamp for use with-a cylinder hav-- l ing a gapf thereinand having meansin the gap' for-'securing' one end of the plate,4 an elongated housing mounted in -said gap for 'moveinentlto-A ward and away from the said? secured plate end,l said housinghaving alongitudinal groove therein, a bar in *said groove adapted when rocked transversely 'in' one direction to be wedged between one wall of the groove and saidplate backed by the other wall ofthe groove, and com-mon operating -mean-s rfor exerting the clam-ping action of said bar and -for moving' the housing inthe plate tensioning direction;

4. In a plate clamp for useA in a cylinderhaving a' gap therein and having means lin ther gap for secu-ring one end oftheplate, an elongated housi-ng mounted'toslide in said gap towardk and away'l from thesecured endv of the plate, said housing having a longitudinal groove therein, afbar in said groove adapted when rocked transversely in one directionto be wedged betweenone wall ofZ the groove7 and said plate backed by the other wall'of the groove, and com-mon operating means for exerting the clampingaction of saidV bar and' for sliding the housingy in the plate tensioning direction'. Y

5. In a plate clamp for use with a cylinder having a gap therein and lhaving means in the gap for securing' one endof thel plate, an elongated housing adapted to be mounted in said gap formovernent toward and away from the secured' end of the plate, said housing havingA a longitudinal groove therein, a bar in said groove adapted when rocked' transversely in one direction to be wedged-1 between one wall ofthe groove and'said' plate .backed'by the. other wall of the grocveandv common operating means for exerting 'force to rock said bar to grip .the plate, and thereafter Yfor exerting force through the bar upon. said housing to move the latter in the plate tension.. ing. direction.

6. In aplate clampfor use ina cylinder havingl a. gapl therein elongated housingsfadapted .tobe. mounted ins-aid gap for movement toward and. away from each other, said housings having elongated groovesg, clamping bars inv each;` of' said grooves adapted when,` roclredil transversely in one? direction Vtofbe wedged between oneA wall of the groove and` said! platebackedby the other wall' ofi the groove and common operating means for exerting the gripping action of a bar and moving the corresponding housing in the plate. tensioning-direction. Y, .i 1 I" i p i 7. Ina plate clamp. for use with acylnder hayy inga gapjtherein and'haVingmeans in the gap for securing-oneen'd ofthe plate, an, elongated housing mounted in said gapfor movementltoward and away from the said secured .end of the .plate, said housing having a longitudinal groove therein, a bar in said groove adapted to berocked transversely for clamping the other end ofthe plate against onev wall of said groove, commonv operating means forj exerting force to rock said bar to grip the plate, and thereafter for exerting force through the bar. upon said housing to move the latter in the plate tensioning direction, and spring means for rocking said .bar in the oppositedirection when the force exerted by said operating means is relieved.

8. In a plate clamp for use with a cylinder having a gap therein and having means for securing one end ofthe plate, an elongated housing adapted to be mounted in the gap, said housing having a longitudinal groove therein, a bar disposed longitudinally in said groove adapted to be rocked transversely, said housing being adapted to receive and hold the other end of the plate between said bar and a wall ofthe groove, said bar having opposed cani surfaces, the distance between the low spotspf said cam surfaces being less than the width of said groove minus the thickness of the plate and the distance between the high spots being greater than the width of the groove minus the thickness of the plate. whereby the rocking of thebar in one direction causes the plate to be gripped between the bar and the housing and the rocking of the bar inthe opposite direction releases the plate.

9..In mechanism of the character described. an elongated housingV having a longitudinal groove therein, a bar disposed longitudinally in said. groove adapted to be rocked transversely, said housing being adapted to receive and hold one end of a printing plate between said bar and a wall ofthe groove, the plate engaging surface of the bar being cam shaped and interengaging means between the housing and the bar on the side of the groove remote from its plate-engaging wall for providing an abutment against which the bar may bear when it is rocked in a direction to increase plate holding pressure. y

. l0. In plate clamping means, a housing having a groove therein formed with cppositely disposed walls, said groove being adapted to receive the end .of the plate to be clamped, a bar in said groove adapted when rocked transversely in one direction to be. wedged between one wall of the groove and said plate backed by the other wall of thegroove, and when rocked in the opposite direction to release said plate, and means operative Whenthe bar is turned in the plate clamping direction to prevent slipping of the bar on the rst said wall in a direction to cause release of y `11. In plate clamping means, a housing having a groove therein formed with oppositely disposed walls, said groove being adapted to receive the end' of the plate to be clamped, a bar in said groove adapted when rocked transversely in one direction to'be wedged betweenone wall of the groove and said plate. backedby the other wall of the groove, and when rocked in the opposite direction to release said plate, means 'operative to prevent slipping of vthe bar on said first named wall-in a direction to cause release of said plate, and means to selectively retain said bar in plate clamping or plate releasing position.

1,2.l In plate clamping means, a housing movable in plate loosening and plate tensioning directions, spring means tending to move said housingjin the plate loosening direction, said housing having a groove therein formed with oppositely disposed walls, said groove being adapted to receivetheend of the plate to be clamped, a bar in said groove adapted when` rocked transversely inv one direction to be wedged between one wall of the groove and said plate backed by the other wall of the groove, and when rocked in the opposite direction to release said plate, spring means tending to turn said bar in its plate releasing direction, and positive means operable by engagement with said bar to turn the latter in plate clamping direction against the resistance of its spring and thereafter to move the housing in the plate tensioning direction against the resistance of said first named spring.

13. In mechanism of the character described,

an elongated housing having a longitudinal groove therein, a bar in said groove having a cam surface adapted when the bar is rocked transversely to wedge the bar between one wall of the groove and an lend of a printing plate backed by the other wall of the groove, `said housing being movable bodily for plate tensioning purposes, and common operating means for exerting the clamping action of said bar and for moving the housing in the plate tensioning direction.

14. In mechanism of the character described, an elongated housing having a longitudinal groove therein, a bar in said groove adapted when the bar ,is rocked transversely to be wedged between one wall of the groove and a printing plate backed bythe other wall of the groove, said housing being movable bodily for plate tensioning purposes, and common operating means for exerting force to rock said -bar to ygrip the plate and thereafter for exerting force through the bar upon said housing to move the latter in the plate tensioning directi0n.

15. In plate clamping means, a housing having a groove therein formed with oppositely disposed walls, said groove being adapted to receive the end of the 'plate to be clamped, and a bar in said groove adapted when rocked transversely in one direction to be wedged between one wall of the groove and said plate backed by the other wall of the1groove,-and when rocked in the opposite direction to release said plate, said housing and said bar. comprising Vcooperating abutment means operative, when force is applied to the bar tending to turn'it in the plate clamping direction, to prevent displacement of the bar in a direction to cause release of said plate.

16. In plate clamping means, a housing having a groove therein formed with oppositely disposed walls, said vgroove being adapted to receive the end ofthe plate'to vbe clamped, a round bar in said groove adapted when rocked transverselyl in one direction to 4be wedged between one wall of thegroove and said plate backed by the other wall of the groove; and when rocked in the opposite direction to release said plate, said bar and said housing being provided with cooperating abutment means about which said bar may be rocked.

-f CHARLES W- HARROLD. f V V*EARL w. CURTIS. 

